Summary of Work: Epidemiological and clinical evaluations of patients with Vilyuisk encephalopathy residing in Iakuta Siberia have been conducted on two occasions during this reporting period. Blood, CSF and autopsy specimens have been collected for in vivo and in vitro isolation studies and for histopathological and immunohistochemical analysis. Molecular genetics of Guamanian ALS and PD using DNA from 150 patients and more than 200 DNA markers in the search for a susceptibility gene. With the retirement of Dr. Gajdusek and the departure of Dr. Yanagihara to the University of Hawaii and Dr. Garruto to SUNY, Birmingham New York, this project is terminated, effective September 30, 1997.